Treatment of hides

ABSTRACT

A process and apparatus for the treatment of hides and skins ( 3 ). The hide or skin is placed on a support ( 1, 2 ) and sealed to the support around the edges of the skin or hide. A treatment liquor is then supplied under pressure between the skin or hide and the support to distend and stretch the skin or hide to permit the more rapid penetration of the treatment liquor into the skin or hide.

TECHNICAL FIELD

This invention relates to an improved treatment of hides and skinsincluding green or dehydrated skins and hides, which for conveniencewill be called ‘skins and hides’ throughout the specification.

BACKGROUND ART

Skins and hides have been treated to produce leather for centuries, anda typical tanning process generally includes the curing of the greenskin or hide by salting or drying prior to shipping to the tannery. Atthe tannery the cured skins are soaked in water to remove the salt andalso any blood and dirt. This soaking may take from hours to seven daysdepending on the condition of the skins. The flesh is then removed fromthe inner surface and to loosen the hair the skin is immersed in asolution of lime and sodium sulphide from one up to nine days followingwhich the hair is removed by a dehairing machine.

Also it is often necessary to pass the skin or hide through a drycleaning solution to remove the fats and proteins from the skin or hide.

The skins or hides are then soaked in a weak solution of acid andsimultaneously most skins are subject to a bating process. Followingthis the skins or hides are tanned, either by vegetable tanning whichmay take several weeks or months, or by chrome tanning which may becompleted in a single day, the tanning involving the immersion of theskins or hides in two different liquors in a tumbling drum.

The leathers can then be lubricated and dyed, with final drying onstretching frames.

In our previous application PCT/AU97/00262 there is described a processand apparatus for the treatment of skins or hides which includes theselection of a skin or hide, stretching the skin or hide by toggles on aframe to a desired configuration and applying a chamber to the upperside of the skin or hide, sealing the chamber to the skin or hide andapplying a pressurised liquor in the chamber so that the liquorpenetrates the skin or hide. Means are provided on the undersurface ofthe skin or hide to support the distended skin or hide and also to sensethe presence of the liquor penetrating the skin or hide to providecontrol of the treatment of the skin or hide.

However the treatment liquor must be applied to the inside of the skinor hide, that is the side opposite to the outer or wool or hair side ofthe skin or hide. Thus in the above specification the liquor is appliedto the upper side of the skin or hide and the lower side of the skin orhide has the wool or hair attached thereto.

In tanning operations it is necessary for the wool or hair to be removedfrom the skin or hide, and in the above described process this can onlybe done when the skin or hide is removed from the toggles and the hairor wool removed before the next tanning process and the skin againattached to the toggles to maintain the stretched condition during thesubsequent tanning or other treatment processes by being passed fromtreatment station to the next.

It is an object of the invention to provide a skin or hide treatmentprocess or tanning process in which the process can be achieved at onestation.

It is another object of the invention to provide a process and apparatuswhereby the wool or hair can be easily removed without removal of theskin or hide from the apparatus.

It is a still further object of the invention to provide a process forthe treatment of skins or hides whereby the process can be controlledwith precision.

Another object of the invention of the invention is to provide a methodand apparatus wherein the time required for treatment and tanning of theskin or hide is considerably reduced.

A still further object of the invention is to provide a method andapparatus wherein the skin or hide is treated in a stretched condition,the skin or hide remaining in the stretched condition after treatment.

Another object of the invention is to stretch the skin or hide bypressurised liquor so that fibres and cells of the skin or hide areopened to whereby the treatment liquor readily penetrates the skin orhide.

A further object of the invention is to provide a process and apparatusfor the treatment of skins or hides in which the treatment liquors arerecycled and/or processed to collect the materials removed from the skinor hide by the processing liquor.

A still further object of the invention is to a process and apparatus inwhich the pressure applied to the liquid not only accelerates the entryof the liquor into the skin or hide, but also provides the means ofstretching the skin or hide to open the fibre structure.

DISCLOSURE OF THE INVENTION

Thus there is provided according to the invention a process for thetreatment of skins or hides, the process including the steps ofpositioning the skin or hide on a frame, with the flesh side adjacentthe frame, sealing the edges of the skin or hide to the support,applying treatment liquor under pressure between the skin or hide andsupport whereby the skin or hide is distended and stretched by theliquor under pressure to open the structure of the skin or hide topermit penetration of the treatment liquor into the skin or hide.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more fully describe the invention reference will now be madeto the accompanying drawings in which:

FIG. 1 is a schematic view of the support, skin or hide and sealingframe

FIG. 2 is side view of one form of support

FIG. 3 is a side view of another form of the invention

FIG. 4 is a partial view of the seal and skin or hide prior to sealing

FIG. 5 is a side view of the seals and,

FIG. 6 is a view of the skin or hide being sealed to the support.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to FIG. 1, the support 1, which for simplicity is illustratedas a table, has a fixed seal 2, to be described in more detail later,generally in the shape of the skin or hide 3 to be treated. The skins orhides are sorted into various sizes and thus the skin or hide will begenerally of a size to be treated according to the invention. A seriesof pins 4 or functional alternative such as a serrated edge arepositioned closely adjacent the seal 2, the purpose of the pins being tolocate the skin or hide prior to the sealing of the skin or hide to thesupport by a sealing frame 5. The sealing frame 5 in this embodiment isan open frame so that during the process of the invention the skin orhide can stretch under inflation as shown in dotted lines in FIG. 2.

The skin or hide 3 is placed on the support and the skin or hide pinnedin position either manually or mechanically which may be automatic ormanually controlled. The sealing frame is then lowered and seals theskin or hide to the support. Although not shown the sealing frame may bemounted on the support, for example by a parallel linkage arrangement sothat it can be raised and swung away from the support. Alternately thesealing frame can be mounted on vertical posts which may be telescopicto enable the sealing frame to be raised and lowered.

A port 6 is provided in the support 1 through which a treating liquor issupplied under pressure. The skin is thus distended and stretched, theamount of stretch being up to 15% or more. The stretch thus opens theskin and the fibres are thus separated which permits the entry of thetreating liquor to penetrate into the skin or hide. The skin or hidemaybe fully penetrated within a few minutes or less, compared with manyhours with conventional processes.

FIG. 3 illustrates a further embodiment of the invention for thetreatment of sheep skins. The skin 7 is placed in position, and a hood 8having an inlet 9 is then placed over the skin and seals onto thesealing frame 5. While the skin is stretched with a treatment liquor, ascouring liquid is then passed into the hood to scour the wool. In thisway the scouring can take place as part of the treatment process of theskin without the scouring having to be undertaken as a separate process.Also if desired as shown in FIG. 3, the treatment liquor can berecirculated by means of a pump, so that there is a continuous supply oftreatment liquor, and which circulation assists in removing materialobtained from the hide or skin during the treatment process.

Also it is preferred that the treatment liquor be continually passedover the surface of the skin, preferably in a turbulent motion. A baffleor baffles may be positioned adjacent the inlet or recirculating inletto create a turbulent flow, and also to prevent the direct impingementof the pressurised liquid onto the skin. These baffles may have holesthere through to assist in creating the degree of turbulence.Furthermore there may be a plurality of inlet orifices which may bedirected to produce a turbulent flow across the surface of the skin.

FIGS. 4 to 6 show a preferred seal 2 and co-operating seal 11 in theframe 5. The seal 2 includes a serrated member or blade 12 attached toor clamped in position on the support 1 by annular members 13. Theco-operating seal 11 on the frame 5 includes a resilient ring of rubberor silicon rubber or other resilient material 14 positioned to be abovethe serrated member 12 in the sealing position. The seal 11 alsoincludes a downwardly facing serrated member 15 spaced inwardly of theserrated member 12 so that in the sealing position the skin or hide isdeflected around the serrated member 15 ensuring that the skin or hideis securely held by the two co-operating serrated members 12 and 15. Ithas been found that due to the nature of a wet hide or skin, a suitableseal or clamp must be such that it will grip the skin or hide which isunder tension due to the pressure under the skin or hide. Thus to ensurethat the seal grips the skin or hide, seal must include members whichare rough or serrated so that the gripping member at least partiallyindents or protrudes into the surface of the skin or hide. As shown aserrated member is satisfactory, and preferably the serrated member canbe in the form of a continuous band which can be bent as desired to thecontour of the skin or hide.

In a further embodiment the frame 5 may be a separate frame not mountedon the support to which the skin or hide is attached prior to theseparate frame being positioned on the support. The frame which ismounted on the support, or a separate pressure applying frame is thenlowered and seals on the separate frame and the support. In this wayskins or hides may be attached to a separate frame and then the framewith the skin or hide attached may be removed for removal of the skin orhide from the frame, or for further processing.

In the treatment of skins or hides, it will be seen that most if not allof the steps necessary for the treatment or tanning of skins or hidescan be carried out in a quick and efficient manner, reducing the timerequired from days to hours and even minutes for some treatments.

After positioning the skin or hide, the skin or hide can first betreated with a detergent or dry cleaning procedure to remove the fatsfrom the skin or hide. By removing the fats, the time for the ensuingtreatments is greatly reduced, due to the fact that the presence of fatshinders the penetration of the treatment liquor. Also the processpermits the removal of hair and wool from the skin or hide if the skinor hide is to be treated to be leather. The dehairing liquor is appliedto pressurise the skin or hide, the dehairing liquor thus penetratingthe skin or hide to destroy the hair or wool follicles. With the skin orhide in the stretched condition the hair or wool can be removed bybrushing or by a vacuum pump. However, if the sheep skin is to betreated with the wool remaining to produce products such as rugs ormats, or items of clothing, the wool is not removed but is scoured asdescribed above.

Thus by sequential addition and removal of liquors with the skin in thestretched condition, the skin or hide can be treated. Also by theprocess it is possible to have complete control over the time oftreatment for each skin or hide. If desired the a cleansing solutioneither water or detergent can be applied between each operation of theprocess to remove the previous liquor and to flush away any matterremoved form the skin or hide.

The skin or hide is stretched up to 15% and in order to retain the skinor hide in the stretched condition, the skin or hide is dried. This canbe while positioned on the support. Additionally the skin or hide on theseparate frame may be then positioned on a separate support for thedrying operation. Also a further stretching may be applied to theportion of the hide or the area of the seal

It has been found that with most hides and skins the thickness isgreater along the back in the spine area. To produce a hide or skin ofuniform thickness, the hide or skin can be stretched longitudinallyalong the central area by tensioning the hide or skin longitudinallywhen being attached to the pins. This tensioning can be done manually ormechanically by attaching toggles to the relevant portion of the hide orskin.

However it in many instances the use of the pins may not be required,the skin or hide is placed in position without tension, and by pressingthe hide onto the serrated seal member the skin or hide is held inposition while the sealing framed is lowered and sealed onto the skin orhide. However if longitudinal tensioning is required along the spinearea of the skin or hide, then pins can be positioned a the appropriateareas to which the skin or hide can be pinned after stretching.

Also it is preferred that the treatment liquor be continually passedover the surface of the skin, preferably in a turbulent motion, thisbeing more desirable when removing the fats and proteins by a detergentsolution. A baffle may be positioned over the inlet or recycling inletto prevent the direct impingement of the pressurised liquid onto theskin. The baffles may have holes or inclined orifices to assist increating the turbulent flow, and also there may be a plurality of inletorifices to assist in creating a flow of detergent over the surface ofthe skin. It has been found that the pressure of the liquid under theskin or hide need only be in the order of 1 psi, although higherpressures may be desirable in some instances.

Also, it is within the scope of the invention that the skins or hides tobe treated are green skins or hides, without have been salted forpreservation.

Also the liquors are recycled and stored for the next treatmentoperation, thus being more environmentally friendly. Additionally theliquor used for the removal of the fats and proteins can be subject tofurther treatment to remove the fats and proteins which themselves are avaluable commodity.

Thus it will be seen that there is provided according to the invention aprocess and apparatus for the treatment of hides and skins by which theprocessing and treatments times are greatly reduced.

What is claimed is:
 1. A process for the treatment of skins or hides,comprising the steps of: providing a frame having a sealing membercorresponding to the profile of the skin or hide; positioning the skinor hide on the frame with the flesh side adjacent to the frame; sealingthe edges of the skin or hide to the frame with an open sealing frame;and applying treatment liquor under pressure between the skin or hideand the frame, whereby the skin or hide is distended and stretched bythe liquor under pressure to open the structure of the skin or hide topermit penetration of the treatment liquor into the skin or hide.
 2. Aprocess as defined in claim 1 wherein the treatment liquor is adetergent or drycleaning solution applied to the skin or hide tosubstantially remove the fats and proteins therefrom.
 3. A process asdefined in claim 1 wherein the treatment liquor is dehairing liquorapplied between the frame and the skin or hide to loosen the wool orhair follicles, and removing the wool or hair while the skin or hide ispositioned in the distended and stretched condition on the frame.
 4. Aprocess as defined in claim 1 wherein the skin or hide is a sheep skin,including the step of positioning a cover over a sheep skin, sealing theedges of the cover to the skin, and applying a scouring liquid into thecover to scour the wool.
 5. A process as defined in claim 1 includingthe stops of applying a treatment liquor to the skin or hide to stretchand treat the skin or hide, draining said liquor to a reservoir,pressursing said skin or hide with a second treatment liquor, drainingsaid liquor and sequentially repeating the process with furthertreatment liquors.
 6. A process as defined in claim 5 including thesteps of collecting the drained liquor for recycling by reuse onsubsequent skins or hides.
 7. A process as defined in claim 1 furtherincluding the step of collecting the liquor after use to recover fatsand proteins therefrom.
 8. A process as defined in claim 1, includingthe step of applying a tanning treatment liquor to the skin or hide. 9.An apparatus for the treatment of skins or hides, said apparatusincluding a frame having floor, a profiled sealing member on said floorcorresponding to the profile of the skin or hide, an open sealing frameto seal the edge of the skin or hide on the profiled sealing member, andmeans to supply pressurised treatment liquor between the floor and theskin or hide to distend and stretch the skin or hide and thus assist inthe passage of the liquor through the skin or hide.
 10. An apparatus asdefined in claim 9 wherein the profiled sealing member comprises atleast one upstanding rigid serrated sealing edge, and a rubber seal onthe inner surface of the profiled sealing member.
 11. An apparatus asdefined in claim 9 wherein the open sealing frame has a downwardlyfacing seal comprising a rubber sealing member, and positioned adjacentthereto on the inner side of the downwardly facing seal a downwardlyfacing serrated edge extending below the lower surface of the rubbersealing member whereby in operation the rubber sealing member pressesthe skin or hide onto the at least one serrated sealing edge, and thedownwardly facing serrated edge presses the skin or hide below the atleast one serrated edge to deflect and lock and seal the skin or hideedge to withstand the pressure under the skin or hide.
 12. An apparatusas defined in claim 9 wherein the means to supply pressurised liquorthrough the floor comprises a pump delivering the liquor through atleast one delivery aperture in the floor.